The present invention relates to a method for fabricating a field emission device which can be used for a flat panel display, an ultra-high frequency amplifier sensor or an electron-beam-applied instrument.
In order to produce an image display device which can replace the cathode ray tube of existing television receivers, the flat panel display has been under vigorous development for use as an image display device for wall-mounted (tapestry) televisions or high definition televisions (HDTV). Such flat panel displays include liquid crystal devices, plasma display panels or field emission devices, among which the field emission device is widely used due to the quality of its screen brightness and low power consumption.
With a field emission device, since cathode tips (electron generating sources) can be highly integrated at about 10.sup.4 -10.sup.5 tips/mm.sup.2 per unit pixel, very high brightness and high illuminating efficiency can be obtained with low electrical consumption. Field emission devices are expected to be adopted for wall-mounted televisions or HDTV.
The fabrication method of a conventional field emission device will now be described with reference to FIGS. 1A to 1D, in which FIG. 1A is a vertical cross-sectional view showing a hole formation, FIG. 1B is a vertical cross-sectional view showing a grazing angle deposition, FIG. 1C is a vertical cross-sectional view showing a micro-tip deposition, and FIG. 1D is a vertical cross-sectional view showing a completed conventional field emission device.
As shown in FIG. 1A, a cathode 2 is formed in a striped pattern on glass substrate 1 and an insulation layer 3 having a hole 8 with consistent dimensions is formed thereon. A gate electrode 4 having an aperture 6 is then formed on the insulation layer 3.
In FIG. 1B, a release layer 5 is deposited using a grazing angle deposition method.
In FIG. 1C, field emitting micro-tips 7 made of the same material as the cathode are deposited inside the holes in an array formation. The release layer 5 is etched to complete the field emission device, as shown in 1D.
In such a fabricating process, the step of forming the micro-tip array of tens of nanometers in size is the crucial part. At this time, a metal is used as the release layer 5. However, as shown in FIG. 1B, a grazing angle deposition method utilizes a specifically manufactured equipment. Since the thickness of the release layer 5 is fixed, a change in the geometrical structure such as the height of the tip cannot be tolerated, thereby lowering the uniformity of the emitted electrical field. Further, since an electrochemical etching or wet chemical etching process is adopted in removing the metal release layer 5, the residual metal material contaminates the device, causing current leakage in the device, and thereby lowering its reliability.